well first of all, drivetrain loss is not a percentage, it's a set number at a given speed. TT's lose about 60-80hp in the drive line from peak power (300-320hp). lightweight flywheels, wheels, rotors and driveshafts are about as good as it can get, plus removing carrier bearings with a 1 piece drive shaft. also bear in mind that larger diameter rotors and wheel/tires often take more HP to drive, even if they are lighter than stock.

that's the way AWD is, but obviously anything you can do to take out rotating weight and reduce friction will help. simply put, we just have a lot of drive line and it takes a fair amount of power to drive it all.

 

so replacing the materials is all we can do to bump up the efficiency of our powertrain? becuase Mitus has a evo AWD, I thought maybe their rear diff would work better than ours or maybe some gearing can be upgraded..

I didn't have anything in mind specifically but I thought since this topic isin't discussed much that there should be some upgrade that we're missing or any ideas going unnoticed.

-Ian

 

well first of all, drivetrain loss is not a percentage, it's a set number at a given speed. TT's lose about 60-80hp in the drive line from peak power (300-320hp). lightweight flywheels, wheels, rotors and driveshafts are about as good as it can get, plus removing carrier bearings with a 1 piece drive shaft. also bear in mind that larger diameter rotors and wheel/tires often take more HP to drive, even if they are lighter than stock.

that's the way AWD is, but obviously anything you can do to take out rotating weight and reduce friction will help. simply put, we just have a lot of drive line and it takes a fair amount of power to drive it all.

Actualy this has been discused at legnth in the past. And I mean legnth. There are threads that are MANY pages long with Many thoeries and math that goes over my head.

The short of it is that it is NOT a set HP number that is loss no matter what HP the engine is putting out. Some thoerize that while power increases some loss remains static while other losses stay a percentage increasing the loss according to the HP increase.

As More power is put into a system with moving parts more friction IS going to occur. With friction there is heat loss and with the transfer is LOSS of power. So with increases in power come increases in the total lost power.

 

hmm well not to say your lying but there's got to be a way or design that can prevent this. I was contemplating using some other material that has less friction for the gears in the differentials. Again, this would probaly require some major aftermarket support so the money spent on such a campaign probaly wouldn't justify the outcome but ya never know.....oh wait i think i just answered my own question haha.

well, nevertheless, i still believe all is possible and we need someone to give it a good 'ole college try. From what i learned in my physics classes, metal on metal lubricated is very resistant on friction (.07 Uk) while metal on teflon is a shade less restrictive (.04 Uk) and could be our answer. I don't have a universal chart that gives all figures, i'm just pulling this info out of my general physics book that I took 1 1/2 years ago. I'm sure there's a reason why the companies use steel in their gearing systems becuase of cost and durability and then performance of course is put on the backburner. Becuase this would be an aftermarket product, I bet it is still possible to make it cost effective yet still lucrative to do such a thing.

buuuut since this has been talked about so much, I guess we can leave it at that?

Can anyone gimme the hyperlink to such threads so I can research myself? Like I said before, i did search for such subjects as "powertrain upgrades" or "powertrain power loss" but no such luck.

-Ian

 

looked for the thread, can't find it. Imagine that.

 

well, ignoring things such as friction and such "parasitic" losses, the amount of power needed to turn the driveline at a given speed is constant. as we know, 1HP=33,000lb.ft./min. so it is a relative to speed, although the majority is static.

friction does play a major role, synthetic gear oils and a 1 piece CFDS that does not use the stock carrier bearings should free up a considerable amount of power. also the elimination of the 2 center U-joints is a bonus. i remember reading an independant test of royal purple in which an old camaro or mustang or something along those lines shoewd an 11hp and 7lb.ft. increase (if my memory serves me) at the rear wheels. that shouldn't be taken as gospel, but better oils *will* result in lower friction. just food for thought. also the fact that royal purple is an odorless gear oil makes it really nice to work with

but in reality, ANYTHING you can do to reduce rotating mass and friction will be worthwhile.

 

looked for the thread, can't find it. Imagine that.

haha, happy customer #1


yeah, i mean, maybe my idea isn't exactly revolutionary; i bet companies such as porche or fararri use such methods to get the best output for their engines as possible but i don't see why our platform couldn't take advantage of such methods. Carbon Fiber is overused but hell, I bet lubricated CF would make them incredibly strong as well as fluid but the manufacturing process is probally a nightmare to make a planetary gear out of one.

Oh well, maybe my idea will die with me. I don't have the funds nor the time to play with such ideas so I guess this will either die with me or is used already and i'm just talking out of my ass.

 

The way real companies get around the AWD DTL issues is they are not AWD 100% of the time. Only when it's needed is power split up front, then it is all rear once traction is had. Porsche does it, Skyline does it, 3S...not so much

 

The way real companies get around the AWD DTL issues is they are not AWD 100% of the time. Only when it's needed is power split up front, then it is all rear once traction is had. Porsche does it, Skyline does it, 3S...not so much

i think that's a great idea, i'd take that over RWD anyday. Buut becuase our percentage is devided up permenantly, that couldn't be a possible upgrade could it? So we're stuck with this cursed drivetrain then... oh well maybe there's a way to fabricate a hybrid drivetrain somehow, developed by a aftermarket company...

 

I can't believe this is still under debate!!! Ugh. Drive train loss CAN be thought of as constant, more or less. The absolute best way to illustrate this is for everyone to go download CarTest.

It graphically illustrates the power loss in gears based on their ratios. Each gear, at a lower rpm has a set amount of loss. At higher rpms this figure climbs somewhat, but not to a vastly different number.

I just pulled up CT myself... the 1991 TT and VR4, when you make the shift to 2nd at 7000 rpm in 1st, in 2nd gear at that point driveline loss is 50 horsepower. Take 2nd to redline, and it rises to about 80 due to higher friction. These figures are damn near the same for every gear.

The mathematical calcs used to arrive at this figure are buried in the program, but run a few acceleration runs and you'll see that it's pretty damn accurate.

As to losing driveline weight, really, the only component that hasn't been touched on is our axles. There are companies that make lightweight ones, but I do not know anyone running these. That would help a lot.

 

hmm friction and weight/

Your ignoring other factors...

what about inertia? theres other factors too

 

The program doesn't ignore that. It basically calculated our driveline loss at 50 hp at the bottom of 2nd, 3rd, and 4th, which corresponds to 4500 rpm or so in all cases.

At 0 mph, drivetrain loss is of course zero. As speed increases to redline in 1st, the drivetrain loss also rises until it hits 78 at 7000 rpm.

This program is like 500k, has about 500 cars to play with in it, and is a very useful little tool.

The program even accounts for friction from tires, aerodynamic losses, etc. Your speed of course stops rising when the amount of horsepower you have is equalled by the combined frictional and aerodynamic loss, at that point you have reached terminal velocity. Playing around with this shows that our cars stop accelerating at 157... and when these cars first came out, Mitsubishi said top speed was 159.

It's pretty accurate. Playing with tire width reduces friction, so do some of the other parameters, you can reduce the car weight, up the horsepower, etc.

 

The program doesn't ignore that. It basically calculated our driveline loss at 50 hp at the bottom of 2nd, 3rd, and 4th, which corresponds to 4500 rpm or so in all cases.

At 0 mph, drivetrain loss is of course zero. As speed increases to redline in 1st, the drivetrain loss also rises until it hits 78 at 7000 rpm.

This program is like 500k, has about 500 cars to play with in it, and is a very useful little tool.

The program even accounts for friction from tires, aerodynamic losses, etc. Your speed of course stops rising when the amount of horsepower you have is equalled by the combined frictional and aerodynamic loss, at that point you have reached terminal velocity. Playing around with this shows that our cars stop accelerating at 157... and when these cars first came out, Mitsubishi said top speed was 159.

It's pretty accurate. Playing with tire width reduces friction, so do some of the other parameters, you can reduce the car weight, up the horsepower, etc.

is this a program that goes on your palm or on your home pc that is a hypothetical program?

j/w

 

It's a home PC program. Been around for several years, they have a "Cartest2000" program that you can pay for, but I've never seen the need to have anything but the basic program, which is a free download.

 

car test is a fun tool. Yet by NO MEANS is it accurate. Most weight figures are way off, the 1/4 times are also way off, and some of the specs are completely wrong.

Its more for fun, and not for "what if"